This application claims the priority of German Patent Document 100 58 020.3, filed Nov. 23, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention concerns an internal combustion engine of a motor vehicle with a drive train containing a differential and an electric motor integrated in the drive train.
A hybrid power train system to complement an internal combustion engine for a motor vehicle is disclosed in WO 98/31559. The motor is assigned a drive for transmitting a driving torque to one driven wheel, gear change apparatus for producing stepped changes in the drive ratio between the input side on the motor and the output side towards the drive, and an electric motor for supplying the driving torque. Regulating and control units are also provided to compensate for a temporary reduction in the magnitude of the driving torque transmitted from the internal combustion engine by connecting the electric motor. The electric motor is directly connected with the cardan shaft via a clutch. An arrangement of the electric motor in a different place than the one shown is not indicated.
An object of the present invention is to configure and arrange an electric drive in such a way that a simple and cost-effective integration of the electric motor into the power flow of the wheel drive is guaranteed.
This object is attained in accordance with the present invention in that a main shaft of the electric motor is directly connected to gear ring of the differential in a positive and/or non-positive way. This allows the integration of an additional electric drive while completely maintaining the assembly consisting of internal combustion engine, clutch, and gearbox, particularly for two-wheel drive vehicles. Design modifications on the internal combustion engine, clutch, or gearbox are avoided in this way. It is only necessary to couple the electric motor to the gear ring or a driving element of the differential of the drive shaft or the driving wheels.
The integration according to the present invention into already existing wheel drives is relatively simple and inexpensive. In this way, a starting support function, particularly with regard to a start-stop function, a compensation of or addition to the tractive power interruption when shifting the gearbox, a boost function for briefly supporting the driving torque of the internal combustion engine, a recovery of braking energy when coasting or slowing down the vehicle as well as generator operation of the electric motor for charging an energy reservoir are possible even in two-wheel drive vehicles.
For this purpose, it is beneficial to arrange a speed multiplier between the main shaft and the gear ring, wherein the speed multiplier is configured as a positive, non-positive or dynamic transmission. In this way, torque produced by the electric motor can be introduced into the area of its favorable operating point in accordance with the differential speed.
Furthermore, it is beneficial to arrange a clutch between the main shaft and the gear ring, wherein the clutch has a positive and/or non-positive configuration. The electric motor can thus be separated from the drive train. When using a dynamic clutch, it is possible to regulate the ratio of the speeds of the differential and electric motor via the dynamic clutch.
A currently preferred embodiment of the present invention provides for the electric motor to be connected with an energy reservoir and serve as a generator. The existing kinetic energy of the driving vehicle can thus be fed or fed back to the energy reservoir via the generator during a braking process.
It is a particularly important aspect of this invention that the electric motor supplements or replaces a driving torque of the internal combustion engine. On one hand, the shifting process of the gearbox and the associated tractive power interruption of the internal combustion engine can be compensated, and on the other hand the driving power of the electric motor can also be introduced into the drive train at any other operating point.
A currently particularly preferred embodiment of the invention enables a low center of gravity of the entire drive train. This brings along advantages in vehicle dynamics.
Likewise, the electric motor can be integrated into the drive train in the smallest space.
The possibility is created of arranging the drive train in such a way that the heavy components, such as the internal combustion engine and the electric motor, are located in the vehicle center plane.
A particularly preferred development provides for assembling a compact drive train, in which the number of gears is doubled with two gear wheel steps on the differential.